Characterizing lubricant oil degradation using fluorescence signals

ABSTRACT

Methods, systems, and apparatus to diagnose lubrication oil deterioration. In one aspect, a method includes irradiating a lubrication oil sample with a light beam to emit a light-induced fluorescence, detecting and processing the light-induced fluorescence signal to determine a temporal variation of a fluorescence intensity, identifying a steady state of the light-induced fluorescence signal, processing the temporal variation of the fluorescence intensity to determine a lubrication oil parameter, and correlating the oil parameter to a calibration curve to diagnose the lubrication oil deterioration.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of priority to U.S. ProvisionalPatent Application Ser. No. 62/327,558, filed on Apr. 26, 2016, thecontents of which are hereby incorporated by reference.

TECHNICAL FIELD

This specification relates to lubrication oil analysis (LOA) and relatedmethods.

BACKGROUND

Lubrication oil performs two essential tasks. One is to provide ahomogenous protective layer between surfaces that are in relative motionto reduce friction, prevent wear and avoid the catastrophic event ofseizure resulting from mating parts. Another role of lubrication oil isto maintain working parts cool, protect against corrosion and flush awaycontaminants and deposits for the surface of mating parts. Lubricationoil degradation is caused by several factors that include: variation inthe electrical, physical, chemical, and optical properties. The maincauses for the deterioration are a combination of water contamination,oxidation and particle contamination. Several parameters can be used tomonitor the degradation of lubrication oil, such as viscosity, watercontent, total acid number (TAN), total base number (TBN), particlecounting, pH value or others. Other parameters, that correlate well withthe standard parameters, such as viscosity measurements, can also beused to identify varying grades of degradation from real samples ofoils.

Lubrication oil analysis (LOA) is a process used to derive oil analysisdata (for example, physical and chemical properties) from lubricationoil samples obtained from industrial equipment. The industrial equipmentcan contain rotating and moving parts (for example, gear boxes,hydraulic systems, engines, compressors, turbines or other movingparts), such as equipment used in hydrocarbon-producing wells. LOA canreveal viscosity changes, as well as ferrous and nonferrouscontamination. LOA can also indicate corrosion of the equipment, leaksbetween different parts of the equipment, remedial actions, or othercritical machinery diagnostic information. LOA can provide informationabout the useful lifetime of the lubrication oil along with the statusof the lubrication oil. Knowledge of the useful lifetime and the statusof the lubrication oil can be used to ensure the reliability and correctfunctioning of the equipment.

SUMMARY

The present disclosure describes methods and systems for performinglubrication oil analysis (LOA) of a lubrication oil sample. In someimplementations, a method includes irradiating a lubrication oil samplewith a light beam such that a light-induced fluorescence can be emittedfrom the lubrication oil sample, detecting a light-induced fluorescencesignal from the lubrication oil sample, processing the light-inducedfluorescence signal to determine a temporal variation of a fluorescenceintensity, identifying a steady state of the light-induced fluorescencesignal based on the temporal variation of the fluorescence intensity,after identifying the steady state, processing the temporal variation ofthe fluorescence intensity to determine a lubrication oil parameter, andcorrelating the oil parameter to a calibration curve to diagnose thelubrication oil deterioration.

The foregoing and other implementations can each optionally include oneor more of the following features, alone or in combination. In anaspect, the method includes collecting the lubrication oil sample froman industrial equipment. The light beam can be a continuouselectromagnetic wave characterized by a single wavelength. The singlewavelength can be between 200 nanometers and 550 nanometers.

In a further aspect, the method includes converting the continuouselectromagnetic wave into a plurality of step light beams, such thateach step light beam has substantially the same intensity within a timeinterval. The method can further include guiding the light beam at anacute angle on a front surface of a container holding the lubricationoil sample. The method can further include filtering the light-inducedfluorescence signal.

In a further aspect, the method includes capturing the light-inducedfluorescence signal by a fast photodiode. The fluorescence intensity canbe represented as a second order dynamic system. The oil parameter canbe associated to an oil viscosity. The oil parameter can be a dampingfactor of the fluorescence signal. The second order dynamic systemcorresponds to an over-damped oscillator and the damping factor can belarger than 1. The oil parameter can be an undamped natural frequency ofthe fluorescence signal. The second order dynamic system corresponds toan under-damped oscillator and the damping factor can be smaller than 1.

In a further aspect, the method includes comparing the oil parameter topreviously measured oil parameter to determine an oil deteriorationrate. The method can further include determining an estimate of a usefulremaining lifetime of the industrial equipment associated to thelubrication oil sample based on the oil deterioration rate. Theindustrial equipment can be in use in a hydrocarbon-producing wellduring determining the estimate of the useful remaining lifetime of theindustrial equipment. The industrial equipment can be a submersible pumpconfigured to pump fluid uphole from the hydrocarbon-producing well andwherein the submersible pump can be disposed within thehydrocarbon-producing well. In a further aspect, the light beam can begenerated by a laser source.

In some implementations, the present disclosure also provides anon-transitory, computer-readable medium for diagnosing lubrication oildeterioration and storing computer-readable instructions. Theinstructions can be executable by a computer and the non-transitory,computer-readable medium can be configured to: guide a light beam to alubrication oil sample, detect light-induced fluorescence signal fromthe lubrication oil sample, process the light-induced fluorescencesignal to determine a temporal variation of a fluorescence intensity,identify a steady state of the light-induced fluorescence signal basedon the temporal variation of the fluorescence intensity, process thetemporal variation of the fluorescence intensity to determine alubrication oil parameter, and correlate the oil parameter to acalibration curve to diagnose lubrication oil deterioration.

In some implementations, the present disclosure also provides a systemto diagnose lubrication oil deterioration, the system including: amemory and a hardware processor interoperably coupled with the memory.The hardware processor can be configured to: guide a light beam to alubrication oil sample, detect light-induced fluorescence signal fromthe lubrication oil sample, process the light-induced fluorescencesignal to determine a temporal variation of a fluorescence intensity,identify a steady state of the light-induced fluorescence signal basedon the temporal variation of the fluorescence intensity, process thetemporal variation of the fluorescence intensity to determine alubrication oil parameter, and correlate the oil parameter to acalibration curve to diagnose lubrication oil deterioration.

In some implementations, the present disclosure also provides anothersystem to diagnose lubrication oil deterioration, the system including:a light beam generator configured to generate a light beam, a containerincluding a lubrication oil sample, an optical equipment configured toguide the light beam to a face of the container, a fast photodiodeconfigured to detect light-induced fluorescence signal from thelubrication oil sample, and a hardware processor interoperably coupledwith a memory. The hardware processor can be configured to: process thelight-induced fluorescence signal to determine a temporal variation of afluorescence intensity, identify a steady state of the light-inducedfluorescence signal based on the temporal variation of the fluorescenceintensity, process the temporal variation of the fluorescence intensityto determine a lubrication oil parameter, and correlate the oilparameter to a calibration curve to diagnose lubrication oildeterioration.

The details of one or more implementations of the subject matter of thisspecification are set forth in the accompanying drawings and associateddescription. Other features, aspects, and advantages of the subjectmatter will become apparent from the description, the drawings, and theclaims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an example system for characterizinglubricant oil degradation using fluorescence signals.

FIG. 2 is a flow chart of an example of a process for characterizinglubricant oil degradation using fluorescence signals.

FIGS. 3A and 3B illustrate example plots of data associated with anover-damped model of oil samples according to an implementation.

FIGS. 4A and 4B illustrate example plots of data associated with acritically damped model of oil samples according to an implementation.

FIG. 5 is a high-level architectural block diagram of an example of acomputer system for correlating and predicting LOAs in a lubrication oilsample obtained from a hydrocarbon well.

DETAILED DESCRIPTION

Currently, the condition of lubrication oil provides the best possibledetection method for early warning of machine failure. However, themajority of industries use offsite and offline lubrication oil analysis(LOA) to quantify the remaining lifetime of the oil. It would bebeneficial to have an accurate, efficient, and rapid ability to performonsite LOA.

LOA is a process used to derive one or more characteristics (forexample, physical and chemical properties) of a lubrication oil, such aslubrication oil samples obtained from equipment used inhydrocarbon-producing wells. LOA is typically performed offsite andoffline. In some cases, each lubrication oil sample can require a day ormore to fully analyze before one or more of the electrical, physical,chemical, and optical properties can be determined. Changes over time inthe LOA in lubrication oil samples from one or more pieces of equipmentused in hydrocarbon-producing wells can provide data useful to determinethe operational lifetime trends of the equipment. The normal practicefor comparing and validating available lubrication oil analysis data isto leverage technical skill or expertise to numerically interpretlubrication oil analysis data, but does not leverage correlations orrelationships that can be efficiently derived from available lubricationoil analysis data and rapid measurement of lubrication oilcharacteristics. It is important to have an efficient, rapid, and simpleability to derive up-to-date data based on prior LOA lubrication oilanalysis data in order to be able to perform special analysis studiesand to determine, for example and among other things, theearlier-mentioned hydrocarbon resource trends and reduction or increaseof lubrication oil degradation.

At a high level, this disclosure generally describes methods andsystems, including computer-implemented methods, computer programproducts, and computer systems, for predicting lubrication oildegradation of a lubrication oil sample obtained from an equipment usedin a hydrocarbon well. Particularly, the predictions are based ondetermining a damping factor or an undamped natural frequency or both,of a fluorescence signal generated by the lubrication oil sample, whichare directly proportional to the viscosity of the lubricant oil sample.The subject matter described in this specification can be implemented inparticular implementations so as to realize one or more of the followingadvantages. The methods and the systems described in this specificationcan be implemented to diagnose oil degradation in the proximity of ahydrocarbon well, on a regular basis, such as a daily basis, at lowcosts, non-intrusively and on-line. LOA data can be obtained for alubrication oil sample from a particular hydrocarbon well equipment,such as turbine oil. LOA can include physical properties, such aslubrication oil viscosity, which can be leveraged by applications toprovide useful analysis and predictive functions of equipment lifetime.LOA can be performed using minimum amounts of lubrication oil (forexample, turbine oil) for analysis (for example, 1-2 milliliters).

In some implementations, LOA can be used to automatically predict aquantitative value of the remaining useful lifetime of the analyzedlubrication oil sample. The use of LOA is an easy, efficient, and timesaving process of comparing and validating available LOA lubrication oilanalysis data. LOA can be associated to multiple performed actions thatinclude determination of lubrication oil breakthrough, determination oflubrication oil invasion, determination of casing leaks between twohydrocarbon reservoirs, prediction of scale precipitation, monitoringsweep, performing remedial or proactive actions based on LOA lubricationoil analysis data correlations, predictions, or other performed actions.LOA can enhance the efficiency of the performed actions based on LOAlubrication oil analysis data that can be derived or predicted fromrapid and simple measurement of lubrication oil fluorescence. Multipleoil samples extracted from the same equipment at different times (forexample, during a time interval in which the lubricant oil of anequipment was not replenished or replaced) can be used to generate agraphical correlation of respective LOAs. The graphical correlation ofmultiple LOAs can provide data useful for monitoring and adjustingdevelopment of specific hydrocarbon-wells or groups of wells, -plants,-fields, or -reservoirs. For example, the described approach forcorrelating or relating, displaying, and predicting data pertaining toLOAs can be used by one or more elements of an organization to developdifferent actions particular to their assigned function for theorganization.

FIG. 1 is a diagram illustrating an example of a system 100 provided bythe present disclosure. The system 100 of FIG. 1 can be used to performLOA and to derive the damping factor or an undamped natural frequency ofa fluorescence signal generated by the analyzed lubrication oil sample102. In some implementations, the system 100 is covered by a housing103, which provides access to the container 108 holding the lubricationoil sample 102. All components or some components of the system 100 canbe attached to a supporting fixture 105 (for example, a table, a shelf,a frame or any other type of supporting fixture). The example componentsof the system 100 can include a laser source 104, a chopper 106, acontainer 108, a beam dump 110, an optical filter 114, lenses 116, afiber optic 118, a fast photodiode 120 and a computing system 122.

In some implementations, the laser source 104 can generate a light beamas continuous electromagnetic waves 105. The laser source 104 can emitelectromagnetic waves 105 of a single wavelength (for example, laserbeam). In some implementations, the laser source 104 can be a tunablelaser that can emit electromagnetic waves 105 of a plurality ofwavelengths within a range of wavelengths. In some examples, the lasersource 104 can include a polarizing filter 103 that polarizes theelectromagnetic waves 105 that are directed towards the lubrication oilsample 102. The laser source 104 can include a set of one or morereflectors that varies the angle at which the electromagnetic waves 105are delivered from the laser source 104. In some examples, the angle atwhich a laser beam is oriented can be adjusted. The electromagneticwaves 105 can be in the visible light spectrum, in the ultraviolet lightspectrum, or in the infrared light spectrum. For example, thewavelengths of the electromagnetic waves 105 can be within a range of200-550 nanometers.

In some implementations, the laser source 104 can be a continuous wave(CW) collimated laser with a central emission wavelength of 405nanometers and output power of 20 milliwatts. In some implementations,the laser source 104 can be a pulsed-wave laser. The laser source 104 isaligned such that it generates a laser beam incident on the frontsurface of the container 108 (for example, at an angle of 45 degrees tothe plane of the surface in the horizontal direction). The chopper 106can be a mechanical optical chopper. The chopper 106 can be placed inthe optical path of the collimated laser beam 105, before the container108. The chopper 106 can open quickly and remain open for apredetermined period of time. For example, the chopper 106 can convertthe continuous laser beam 105 into a step laser beam 107 with a constantintensity for a particular time interval (for example, 4 minutes or alonger or shorter time duration). A part of the step laser beam 107 isreflected by the walls of the container 108. The reflected laser beamcan be absorbed by a beam dump 110.

The step laser beam 107 crosses the walls of the container 108 toirradiate the lubrication oil sample 102. The container 108 has wallsthat are transparent to the central emission wavelength (for example,405 nanometers). For example, the container 108 can be a quartz cuvette.The container 108 can have multiple geometries that provide at least oneplanar side (for example, a planar front wall 107) that enablesoptimization of the irradiation of the lubricant oil. For example, thecontainer 108 can be square-shaped or rectangular shaped. Thelubrication oil sample 102, irradiated by the step laser beam 107,generates a laser-induced fluorescence signal 112. The fluorescencesignal 112 of the lubricant oil is filtered by the optical filter 114,which is placed parallel to the front wall 107 of the container 108 thatis first crossed by the electromagnetic waves generated by the laser 104(for example, front surface of the container 108). The center of theoptical filter 114 is aligned with the incidence point of the step laserbeam 107 and the front wall 107 of the container 108.

The broadband fluorescence spectrum emission signal (plus or minus 200nanometers) can be optically filtered using the optical filter 114,having a narrow wavelength range (plus or minus 10 nanometers). Forexample, the fluorescence signal 112 can be filtered by the opticalfilter 114 at one wavelength, which is chosen to correspond to afluorescence signal of a reasonable intensity (for example, 440 plus orminus 10 nanometers). The filtered fluorescence signal 112 can becollimated and focused by lenses 116 onto an optical fiber 118. Theoptical fiber 118 can be connected to a fast photodiode 120 to capturethe fluorescence intensity as function of time. The output signal of thephotodiode 120 at the filtered wavelength (for example, 440 plus orminus 10 nanometers) can be acquired and recorded every 20 ms during thetime interval, in which the chopper is open.

The acquired fluorescence signal can be processed by a computing system122. Data post processing can include smoothing, reduction of redundantinformation and fitting algorithms (for example, process 200 describedwith reference to FIG. 2). In some implementations, the computing system122 can be a mobile handheld device. In some examples, the computingsystem 122 and the laser source 104 can be directly connected to andpowered by an external power source (for example, a wall outlet).

In some implementations, the computing system 122 can include a triggersource that is a computer program operable to control one or more of astart time, an end time, and a rate at which the chopper 106 opens andcloses. In some examples, the trigger source can be determined by analgorithm stored within a computer-readable memory of the computingsystem 122. In some implementations, the system 100 can include atrigger source that is housed external to and separately from thecomputing system 122 or affixed to the external surface of the chopper106. For example, the trigger source can be a foot pedal, a switch, abutton, or a lever that allows a user of the system 100 to activate thetrigger source by depressing the pedal, flipping the switch, depressingthe button, or moving the lever, respectively. In some examples, thetrigger source is operable to cause the chopper 106 to deliver a laserbeam with a particular temporal characteristic to the lubrication oilsample 102 when the trigger source is activated by the user of thesystem 100.

FIG. 2 is a flow chart of a method 200 for diagnosing oil deteriorationaccording to an implementation. The method 200 can be executed using thesystems described with reference to FIGS. 1 and 5, in the proximity of ahydrocarbon well. However, it will be understood that method 200 can beperformed, for example, by any other suitable system, environment,software, and hardware, or a combination of systems, environments,software, and hardware as appropriate. In some implementations, varioussteps of method 200 can be run in parallel, in combination, in loops, orin any order.

At 202, an oil sample is collected. The oil sample can be a lubricantoil sample that is collected from an equipment used in a hydrocarbonwell for LOA. The amount of collected oil sample can be smaller than 1centiliters (for example, about 1-2 milliliters). The collection of theoil sample can include placing the oil sample in an opticallytransparent cuvette. The cuvette can be a quartz cuvette with 1 cmoptical path length.

At 204, a light beam is generated. The light beam can be anelectromagnetic wave of a particular wavelength. For example, the lightbeam can be a CW laser radiation. The laser source used to generate theCW laser radiation can be a CW collimated laser with a central emissionwavelength of 405 nanometers and output power of 20 milliwatts. Thelaser can be setup so that it is incident on the front surface of thecuvette and at a preferred incidence angle (for example, 45 degrees) tothe plane of the surface in the horizontal direction. In someimplementations, the laser can be setup in a position that isindependent from the front surface of the cuvette and the light beam isdirected towards the front surface of the cuvette at a preferredincidence angle through an optical system made of one or more lenses andmirrors.

At 206, the continuous light beam is converted into a step light beam.The conversion to step light beam can be done by a mechanical opticalchopper placed in the path of the collimated laser beam, before thecuvette (see FIG. 1). The mechanical optical chopper can provide a steplaser intensity on the sample for a particular time interval (forexample, 4 minutes). At 208, the oil sample is irradiated by the steplight beam. At 210, the resulting laser-induced fluorescence signal fromthe lubricant oil is optically filtered by an optical filter. Forexample, the fluorescence signal can be optically filtered at onewavelength corresponding to a fluorescence signal of reasonableintensity (for example, 440 plus or minus 10 nanometers). At 212, thefiltered fluorescence signal can be collimated and focused onto anoptical fiber, using a combination of lenses.

At 214, the fluorescence signal can be captured by a fast photodiode asfunction of time. The fast photodiode can be synchronized to themechanical optical chopper, such that the fluorescence signal iscaptured while the mechanical optical chopper is open. For example, thephotodiode can acquire and record the fluorescence signal every 20 msonce the mechanical optical chopper is open.

At 216, the fluorescence signal is processed. Data processing caninclude smoothing, reduction of redundant information and fittingalgorithms. Fitting algorithms are based on the type of oil that isanalyzed. Each type of oil is associated to a particular temporalvariation of the fluorescence intensity. For example, some oils do notproduce a damping effect. In case no damping effect is produced, thenatural frequency can be measured. Some oil samples produce anoverdamped effect. In case an overdamped effect is produced, the naturalfrequency or the damping factor (>1) or both can be measured. And athird type of oils produce underdamped behavior, in which the naturalfrequency or the damping factor (<1) or both can be used. Fordetermining a damping factor, the fluorescence signal is treated as asecond order system. An example second order differential equation thatcan be used to describe the behavior of the second order fluorescenceresponse is:

{umlaut over (x)}+2ζω_(n) {dot over (x)}+ω _(n) ² x=f(t)  (Eq. 1)

In Eq. 1, x is the response of the system, in this case thetime-dependent fluorescence response of the oil, ω_(n) is the un-dampednatural frequency during the transient response, ζ is the damping factorof the fluorescence response and f(t) is the applied function to thesystem, in this case the incident laser radiation.

To examine the transient response of the induced fluorescence signal aunit step function u(t) can be applied to represent the sudden onset ofthe laser:

$\begin{matrix}{{f(t)} = {{u(t)} = \left\{ \begin{matrix}{{0\mspace{14mu} {for}\mspace{14mu} t} < 0} \\{{1\mspace{14mu} {for}\mspace{14mu} t} \geq 0}\end{matrix} \right.}} & \left( {{Eq}.\mspace{14mu} 2} \right)\end{matrix}$

In Eq. 2, for time <0, the laser is off, and for time ≧0, the laser ison, in continuous wave mode. Accordingly the second order differentialequation for the time-dependent fluorescence response (Eq. 1) becomes:

{umlaut over (x)}+2 ζω_(n) {dot over (x)}+ω _(n) ² x=u(t)  (Eq. 3)

In Eq. 3, u(t) is the previously described step function.

At 218 a steady state of the light-induced fluorescence signal isidentified based on the temporal variation of the fluorescenceintensity. The steady state value of the light-induced fluorescencesignal can indicate if the time-dependent fluorescence responsecorresponds to an over damped system or a critically damped system. Insome implementations, the time-dependent fluorescence responsecorresponds to an over damped system. In the case of an over dampedsystem, the damping factor is greater than one (ζ>1) the over-dampedstep response can be expressed as:

$\begin{matrix}{{x(t)} = {\frac{1}{\omega_{n}^{2}}\left\lbrack {1 + {\frac{1}{2\sqrt{1 - \zeta^{2}}}\left( {{\frac{1}{{- \zeta} + \sqrt{\zeta^{2} - 1}}e^{{- {\omega_{n}{({\zeta - \sqrt{\zeta^{2} - 1}})}}}t}} + {\frac{1}{\zeta + \sqrt{\zeta^{2} - 1}}e^{{- {\omega_{n}{({\zeta + \sqrt{\zeta^{2} - 1}})}}}t}}} \right)}} \right\rbrack}} & \left( {{Eq}.\mspace{14mu} 4} \right)\end{matrix}$

Eq. 4 is the solution of the damped equation for the over-damped casesystem response, where all the initial conditions are assumed to bezero.

In some implementations, the time-dependent fluorescence responsecorresponds to a critically damped system. The solution of Eq. 2 for thecritically damped case, in which the damping ratio is equal to one(ζ=1), is expressed as follows:

$\begin{matrix}{{x(t)} = {\frac{1}{\omega_{n}^{2}}\left\lbrack {1 - {e^{{- \omega_{n}}t}\left( {1 - {\omega_{n}t}} \right)}} \right\rbrack}} & \left( {{Eq}.\mspace{14mu} 4^{\prime}} \right)\end{matrix}$

In Eq. 4′ all the initial conditions are assumed to be zero.

At 220, after the identification of the steady state, an oil parameteris determined. The oil parameter can include the damping factor and theundamped natural frequency of the fluorescence signal. For example, theresults of the analysis of the temporal response of the laser inducedfluorescence of lubrication oil as a second order system (including asteady state phase) can be used to provide the oil parameter associatedto the over-damped or undamped natural frequency of the response. Inparticular, the damping ratio can be used as a parameter for oilcharacterization. In some implementations, the determined oil parametervalues are displayed to a user analyzing the oil sample and stored in asuitable persistent memory storage, such as a database. Steps 202 to 220can be repeated for multiple samples (including a fresh sample anddeteriorated samples) of the same type of oil, extracted at differenttimes from a particular equipment.

At 222, the oil parameter is used to determine the degradation of theoil. At 224, the degradation of the oil is used to determine the usefulremaining lifetime of the oil (for example, days, weeks, months oryears). The useful remaining lifetime of the oil can be determined bycorrelating the change in the measured damping factor or the naturalfrequency to the calibration curve for each type of oil. For aparticular type of oil, the damping factor or the undamped naturalfrequency of the fluorescence signal of one fresh sample can be comparedto the corresponding parameters of multiple deteriorated samples of thesame oil type. For those oils that produce a damping effect, the dampingfactor of the fresh sample (for example, 1.26 radians/second) can beused as a reference point and as the value of the damping factorincreases above the corresponding threshold (for example, 3.3radians/second) it can indicate that the oil is degraded beyond use andreplacement is recommendable. For those oils that are characterized byan underdamped behavior, the natural frequency of a fresh sample of onetype of lubrication oil (for example, 3.36 radians/second) can be usedas a reference point for the corresponding type of lubrication oil. Avalue of the natural frequency that exceeds a particular threshold (forexample, 8.5 radians/second) can indicate that the oil is degradedbeyond use and replacement is recommendable. In some implementations,the estimated useful remaining lifetime of the oil is provided (forexample, displayed) to a user analyzing the oil sample and stored in asuitable persistent memory storage. In some implementations, the resultsof the process 200 are stored in sets corresponding to each equipmentassociated to the tested oil degradation. The records can be used tofind the rate of increase in the natural frequency or in the dampingfactor for each equipment and convert the degradation rate into theestimate of the useful remaining lifetime. The determined LOA data (forexample, oil parameter) can be stored as a backup in any suitablepersistent memory storage, such as a database. For example, in someimplementations, the backup data can be stored in an offsite datarepository, in a separate local or remote database, or within a machineassociated database.

The use of any suitable programming language is considered to be withinthe scope of this disclosure. LOA lubrication oil analysis data can beretrieved (for example, using a suitable database query language) fromearlier database to determine a degradation rate. Processing can includea repetition of steps 202-224 at different times (corresponding todifferent degradation rates) and an estimated useful remaining lifetimeof the oil is provided (for example, displayed). Output of the method200 can be provided in a standard tabular format, but other formats arepossible and considered to be within the scope of this disclosure.

The method 200 can be used to determine relationships between the LOAparameters (for example, natural frequency or the damping factor)associated with the existing LOA lubrication oil analysis data (forexample, viscosity) and then graphically display the determinedrelationship results using a graphical technique, as described withreference to FIGS. 3B and 4B.

FIG. 3A illustrates an example fit for the over-damped modelcorresponding to an oil sample 300 a. Fluorescence intensity 302 a isdisplayed as a function of time with a selected time resolution (forexample, 20 ms). The term w corresponds to the best fit frequency inradians/second and d is the damping factor. In some implementations, asimilar graph can be displayed to a user analyzing a particular oilsample, according to method 200. The example display can allow a rapid,visual analysis of the presented data.

FIG. 3B illustrates an example experimental validation 300 b of method200 for an over-damped system, described with reference to FIG. 2. Theexperimental validation tests the relationship between damping factors302 b determined using method 200 and kinematic viscosities for aplurality of oil samples. Experimental validation tests were performedon 4 different samples of turbine lubricant oils taken from the sameequipment, at different times (for example, corresponding to differentlevels of deterioration). The kinematic viscosity (at 40° C.) anddensity (at 20° C.) were measured using ASTM D-7024 and D-4052,respectively, and are listed in Table 1. Data reduction algorithm wasused to reduce the number of points by 5 times before a best fit for Eq.4 was carried out to obtain the oscillation frequency for each of thesamples. The damping factor of the oils tested was found to increasewith viscosity. A plot of the oscillator frequency vs. viscosity, asshown in FIG. 3B shows a linear correlation of R² values (for example,coefficient of determination) better than 96%. The linear correlationbetween the oil parameter and viscosity, as illustrated in FIG. 3Bindicates that method 200 can be used to measure the deteriorationcondition of the lubricant oil. The relationship between the dampingfactor, density and kinematic viscosity can also be used to determinethe viscosity of turbine oil in-situ for each analyzed oil sample.

TABLE 1 Density at 20° C. Kinematic viscosity at 40° C. Sample 1 0.873931.476 Sample 2 0.8716 32.605 Sample 3 0.8737 33.243 Sample 4 0.873733.270

FIG. 4A illustrates an example fit for the critically-damped modelcorresponding to an oil sample 400 a. Fluorescence intensity 402 a isdisplayed as a function of time with a selected time resolution (forexample, 20 ms). The term w corresponds to the best fit fluorescenceoscillation frequency in radians/second. In some implementations, asimilar graph can be displayed to a user analyzing a particular oilsample, according to method 200. The example display can allow a rapid,visual analysis of the presented data.

FIG. 4B illustrates an example experimental validation 400 b of method200 for a critically damped system, described with reference to FIG. 2.The experimental validation tests the relationship between undampednatural frequencies (expressed in radians/second) 402 b determined usingmethod 200 and kinematic viscosities for a plurality of oil samples.Experimental validation tests were performed on 5 different samples ofturbine lubricant oils taken from the same equipment, at different times(for example, corresponding to different levels of deterioration). Thekinematic viscosity (at 40° C.) and density (at 20° C.) were measuredusing ASTM D-7024 and D-4052, respectively, and are listed in Table 2.

TABLE 2 Kinematic viscosity at Density at 20° C. 40° C. Sample 1 0.873931.476 Sample 2 0.8716 32.605 Sample 3 0.8723 32.850 Sample 4 0.873933.084 Sample 5 0.8739 33.122

Data reduction algorithm was used to reduce the number of points by 5times before a best fit for Eq. 4′ was carried out to obtain theoscillation frequency for each of the samples. The fluorescenceoscillation frequencies of the tested oils were found to increase withviscosity. A plot of the oscillator frequency vs viscosity is shown inFIG. 4B, which shows a logarithmic correlation of R² values (forexample, coefficient of determination) better than 94%. The linearcorrelation between the oil parameter and viscosity, as illustrated inFIG. 4B indicates that method 200 can be used to measure thedeterioration condition of the lubricant oil. The relationship betweenthe undamped natural frequency, density and kinematic viscosity can alsobe used to determine the viscosity of turbine oil in-situ for eachanalyzed oil sample.

FIG. 5 is a block diagram 122 of an exemplary computer 502 used forpredicting lubrication oil degradation based on LOA in a lubrication oilsample according to an implementation. The illustrated computer 502 isintended to encompass any computing device such as a server, desktopcomputer, laptop or notebook computer, wireless data port, smart phone,personal data assistant (PDA), tablet computing device, one or moreprocessors within these devices, or any other suitable processingdevice, including both physical and virtual instances of the computingdevice. Additionally, the computer 502 may comprise a computer thatincludes an input device, such as a keypad, keyboard, touch screen, orother device that can accept user information, and an output device thatconveys information associated with the operation of the computer 502,including digital data, visual and audio information, or a graphicaluser interface (GUI).

The computer 502 can serve as a client, network component, a server, adatabase or other persistency, or any other component of a computersystem for predicting lubrication oil degradation based on LOA in alubrication oil sample. The illustrated computer 502 is communicablycoupled with a network 530. In some implementations, one or morecomponents of the computer 502 may be configured to operate within acloud-computing-based, local, global, or other environment.

At a high level, the computer 502 is an electronic computing deviceoperable to receive, transmit, process, store, or manage data andinformation associated with predicting lubrication oil degradation basedon LOA in a lubrication oil sample. According to some implementations,the computer 502 may also include or be communicably coupled with anapplication server, e-mail server, web server, caching server, streamingdata server, business intelligence (BI) server, or other server.

The computer 502 can receive requests over network 530 from a clientapplication (for example, executing on another computer 502) and respondto the received requests by processing the said requests in anappropriate software application. In addition, requests may also be sentto the computer 502 from internal users (for example, from a commandconsole or by other appropriate access method), external or thirdparties, other automated applications, as well as any other appropriateentities, individuals, systems, or computers.

Each of the components of the computer 502 can communicate using asystem bus 503. In some implementations, any or all the components ofthe computer 502, both hardware and software, may interface with eachother or the interface 504 over the system bus 503 using an applicationprogramming interface (API) 512 or a service layer 513. The API 512 mayinclude specifications for routines, data structures, and objectclasses. The API 512 may be either computer language-independent or-dependent and refer to a complete interface, a single function, or evena set of APIs. The service layer 513 provides software services to thecomputer 502 and other components (whether or not illustrated) that arecommunicably coupled to the computer 502. The functionality of thecomputer 502 may be accessible for all service consumers using thisservice layer. Software services, such as those provided by the servicelayer 513, provide reusable, defined business functionalities through adefined interface. For example, the interface may be software written inany suitable language providing data in extensible markup language (XML)format or other suitable format. While illustrated as an integratedcomponent of the computer 502, alternative implementations mayillustrate the API 512 and the service layer 513 as stand-alonecomponents in relation to other components of the computer 502 and othercomponents (whether or not illustrated) that are communicably coupled tothe computer 502. Moreover, any or all parts of the API 512 and theservice layer 513 may be implemented as child or sub-modules of anothersoftware module, enterprise application, or hardware module withoutdeparting from the scope of this disclosure.

The computer 502 includes an interface 504. Although illustrated as asingle interface 504 in FIG. 5, two or more interfaces 504 may be usedaccording to particular needs, desires, or particular implementations ofthe computer 502 and functionality for predicting lubrication oildegradation based on LOA. The interface 504 is used by the computer 502for communicating with other systems in a distributed environment thatare connected to the network 530. Generally, the interface 504 compriseslogic encoded in software and hardware in a suitable combination andoperable to communicate with the network 530. More specifically, theinterface 504 may comprise software supporting one or more communicationprotocols associated with communications such that the network 530 orinterface's hardware is operable to communicate signals within andoutside of the illustrated computer 502.

The computer 502 includes a processor 505. Although illustrated as asingle processor 505 in FIG. 5, two or more processors may be usedaccording to particular needs, desires, or particular implementations ofthe computer 502. Generally, the processor 505 executes instructions andmanipulates data to perform the operations of the computer 502.Specifically, the processor 505 executes the functionality forpredicting lubrication oil degradation based on LOA in a lubrication oilsample.

The computer 502 also includes a memory 506 that holds data for thecomputer 502 and other components that can be connected to the network530. For example, memory 506 can be a database storing LOA lubricationoil analysis data, and data consistent with this disclosure. Althoughillustrated as a single memory 506 in FIG. 5, two or more memories maybe used according to particular needs, desires, or particularimplementations of the computer 502 and functionality to predictlubrication oil degradation based on LOA in a lubrication oil sample.While memory 506 is illustrated as an integral component of the computer502, in alternative implementations, memory 506 can be external to thecomputer 502.

The application 507 is an algorithmic software engine providingfunctionality according to particular needs, desires, or particularimplementations of the computer 502, particularly with respect tofunctionality required for predicting lubrication oil degradation basedon LOA in a lubrication oil sample. For example, application 507 canserve as one or more components, modules, and applications describedwith respect to any of the figures. Further, although illustrated as asingle application 507, the application 507 may be implemented asmultiple applications 507 on the computer 502. In addition, althoughillustrated as integral to the computer 502, in alternativeimplementations, the application 507 can be external to the computer502.

There may be any number of computers 502 associated with, or externalto, a computer system containing computer 502, each computer 502communicating over network 530. Further, the terms “client,” “user,” andother appropriate terminology may be used interchangeably as appropriatewithout departing from the scope of this disclosure. Moreover, thisdisclosure contemplates that many users may use one computer 502, orthat one user may use multiple computers 502.

Implementations of the subject matter and the functional operationsdescribed in this specification can be implemented in digital electroniccircuitry, in tangibly embodied computer software or firmware, incomputer hardware, including the structures disclosed in thisspecification and their structural equivalents, or in combinations ofone or more of them. Implementations of the subject matter described inthis specification can be implemented as one or more computer programs,such as, one or more modules of computer program instructions encoded ona tangible, non-transitory computer-storage medium for execution by, orto control the operation of, data processing apparatus. Alternatively orin addition, the program instructions can be encoded on an artificiallygenerated propagated signal, such as, a machine-generated electrical,optical, or electromagnetic signal that is generated to encodeinformation for transmission to suitable receiver apparatus forexecution by a data processing apparatus. The computer-storage mediumcan be a machine-readable storage device, a machine-readable storagesubstrate, a random or serial access memory device, or a combination ofone or more of them.

The terms “data processing apparatus,” “computer,” or “electroniccomputer device” (or equivalent as understood by one of ordinary skillin the art) refer to data processing hardware and encompass all kinds ofapparatus, devices, and machines for processing data, including by wayof example, a programmable processor, a computer, or multiple processorsor computers. The apparatus can also be or further include specialpurpose logic circuitry, for example, a central processing unit (CPU),an FPGA (field programmable gate array), or an ASIC(application-specific integrated circuit). In some implementations, thedata processing apparatus and special purpose logic circuitry may behardware-based and software-based. The apparatus can optionally includecode that creates an execution environment for computer programs, forexample, code that constitutes processor firmware, a protocol stack, adatabase management system, an operating system, or a combination of oneor more of them. The present disclosure contemplates the use of dataprocessing apparatuses with or without conventional operating systems.

A computer program, which may also be referred to or described as aprogram, software, a software application, a module, a software module,a script, or code, can be written in any form of programming language,including compiled or interpreted languages, or declarative orprocedural languages, and it can be deployed in any form, including as astand-alone program or as a module, component, subroutine, or other unitsuitable for use in a computing environment. A computer program may, butneed not, correspond to a file in a file system. A program can be storedin a portion of a file that holds other programs or data, for example,one or more scripts stored in a markup language document, in a singlefile dedicated to the program in question, or in multiple coordinatedfiles, for example, files that store one or more modules, sub-programs,or portions of code. A computer program can be deployed to be executedon one computer or on multiple computers that are located at one site ordistributed across multiple sites and interconnected by a communicationnetwork. While portions of the programs illustrated in the variousfigures are shown as individual modules that implement the variousfeatures and functionality through various objects, methods, or otherprocesses, the programs may instead include a number of sub-modules,third-party services, components, libraries, and such, as appropriate.Conversely, the features and functionality of various components can becombined into single components as appropriate.

The processes and logic flows described in this specification can beperformed by one or more programmable computers executing one or morecomputer programs to perform functions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, such as, a CPU, an FPGA, or an ASIC.

Computers suitable for the execution of a computer program can be basedon general or special purpose microprocessors, both, or any other kindof CPU. Generally, a CPU will receive instructions and data from aread-only memory (ROM) or a random access memory (RAM) or both. Theessential elements of a computer are a CPU for performing or executinginstructions and one or more memory devices for storing instructions anddata. Generally, a computer will also include, or be operatively coupledto, receive data from or transfer data to, or both, one or more massstorage devices for storing data, for example, magnetic, magneto-opticaldisks, or optical disks. However, a computer need not have such devices.Moreover, a computer can be embedded in another device, for example, amobile telephone, a personal digital assistant (PDA), a mobile audio orvideo player, a game console, a global positioning system (GPS)receiver, or a portable storage device, for example, a universal serialbus (USB) flash drive, to name just a few.

Computer-readable media (transitory or non-transitory, as appropriate)suitable for storing computer program instructions and data include allforms of non-volatile memory, media and memory devices, including by wayof example semiconductor memory devices, for example, erasableprogrammable read-only memory (EPROM), electrically erasableprogrammable read-only memory (EEPROM), and flash memory devices;magnetic disks, for example, internal hard disks or removable disks;magneto-optical disks; and CD-ROM, DVD-R, DVD-RAM, and DVD-ROM disks.The memory may store various objects or data, including caches, classes,frameworks, applications, backup data, jobs, web pages, web pagetemplates, database tables, repositories storing business and dynamicinformation, and any other appropriate information including anyparameters, variables, algorithms, instructions, rules, constraints, orreferences thereto. Additionally, the memory may include any otherappropriate data, such as logs, policies, security or access data,reporting files, as well as others. The processor and the memory can besupplemented by, or incorporated in, special purpose logic circuitry.

To provide for interaction with a user, implementations of the subjectmatter described in this specification can be implemented on a computerhaving a display device, for example, a cathode ray tube (CRT), liquidcrystal display (LCD), light emitting diode (LED), or plasma monitor,for displaying information to the user and a keyboard and a pointingdevice, for example, a mouse, trackball, or trackpad by which the usercan provide input to the computer. Input may also be provided to thecomputer using a touchscreen, such as a tablet computer surface withpressure sensitivity, a multi-touch screen using capacitive or electricsensing, or other type of touchscreen. Other kinds of devices can beused to provide for interaction with a user as well; for example,feedback provided to the user can be any form of sensory feedback, forexample, visual feedback, auditory feedback, or tactile feedback; andinput from the user can be received in any form, including acoustic,speech, or tactile input. In addition, a computer can interact with auser by sending documents to and receiving documents from a device thatis used by the user; for example, by sending web pages to a web browseron a user's client device in response to requests received from the webbrowser.

The term “graphical user interface,” or “GUI,” may be used in thesingular or the plural to describe one or more graphical user interfacesand each of the displays of a particular graphical user interface.Therefore, a GUI may represent any graphical user interface, includingbut not limited to, a web browser, a touch screen, or a command lineinterface (CLI) that processes information and efficiently presents theinformation results to the user. In general, a GUI may include aplurality of user interface (UI) elements, some or all associated with aweb browser, such as interactive fields, pull-down lists, and buttonsoperable by the business suite user. These and other UI elements may berelated to or represent the functions of the web browser.

Implementations of the subject matter described in this specificationcan be implemented in a computing system that includes a back-endcomponent, for example, as a data server, or that includes a middlewarecomponent, for example, an application server, or that includes afront-end component, for example, a client computer having a graphicaluser interface or a web browser through which a user can interact withan implementation of the subject matter described in this specification,or any combination of one or more such back-end, middleware, orfront-end components. The components of the system can be interconnectedby any form or medium of wireline or wireless digital datacommunication, for example, a communication network. Examples ofcommunication networks include a local area network (LAN), a radioaccess network (RAN), a metropolitan area network (MAN), a wide areanetwork (WAN), worldwide interoperability for microwave access (WIMAX),a wireless local area network (WLAN) using, for example, 802.11 a/b/g/nand 802.20, all or a portion of the Internet, and any othercommunication system or systems at one or more locations. The networkmay communicate with, for example, internet protocol (IP) packets, framerelay frames, asynchronous transfer mode (ATM) cells, voice, video,data, or other suitable information between network addresses.

The computing system can include clients and servers. A client andserver are generally remote from each other and typically interactthrough a communication network. The relationship of client and serverarises by virtue of computer programs running on the respectivecomputers and having a client-server relationship to each other.

In some implementations, any or all of the components of the computingsystem, both hardware and software, may interface with each other or theinterface using an application programming interface (API) or a servicelayer. The API may include specifications for routines, data structures,and object classes. The API may be either computer language-independentor -dependent and refer to a complete interface, a single function, oreven a set of APIs. The service layer provides software services to thecomputing system. The functionality of the various components of thecomputing system may be accessible for all service consumers via thisservice layer. Software services provide reusable, defined businessfunctionalities through a defined interface. For example, the interfacemay be software written in any suitable language providing data in anysuitable format. The API and service layer may be an integral or astand-alone component in relation to other components of the computingsystem. Moreover, any or all parts of the service layer may beimplemented as child or sub-modules of another software module,enterprise application, or hardware module without departing from thescope of this disclosure.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anyinvention or on the scope of what may be claimed, but rather asdescriptions of features that may be specific to particularimplementations of particular inventions. Certain features that aredescribed in this specification in the context of separateimplementations can also be implemented in combination in a singleimplementation. Conversely, various features that are described in thecontext of a single implementation can also be implemented in multipleimplementations separately or in any suitable sub-combination. Moreover,although features may be described as acting in certain combinations andeven initially claimed as such, one or more features from a claimedcombination can in some cases be excised from the combination, and theclaimed combination may be directed to a sub-combination or variation ofa sub-combination.

Particular implementations of the subject matter have been described.Other implementations, alterations, and permutations of the describedimplementations are within the scope of the following claims as will beapparent to those skilled in the art. While operations are depicted inthe drawings or claims in a particular order, this should not beunderstood as requiring that such operations be performed in theparticular order shown or in sequential order, or that all illustratedoperations be performed (some operations may be considered optional), toachieve desirable results. In certain circumstances, multitasking orparallel processing may be advantageous and performed as deemedappropriate.

Moreover, the separation or integration of various system modules andcomponents in the implementations described earlier should not beunderstood as requiring such separation or integration in allimplementations, and it should be understood that the described programcomponents and systems can generally be integrated together in a singlesoftware product or packaged into multiple software products.

Accordingly, the earlier provided description of example implementationsdoes not define or constrain this disclosure. Other changes,substitutions, and alterations are also possible without departing fromthe spirit and scope of this disclosure.

What is claimed is:
 1. A method to diagnose lubrication oil deterioration, the method comprising: irradiating a lubrication oil sample with a light beam such that a light-induced fluorescence is emitted from the lubrication oil sample; detecting a light-induced fluorescence signal from the lubrication oil sample; determining a lubrication oil parameter from the light-induced fluorescence signal; and determining an amount of lubrication oil deterioration by correlating the lubrication oil parameter to a calibration curve.
 2. The method of claim 1, wherein determining the lubrication oil parameter further comprises determining a temporal variation of a fluorescence intensity from the light-induced fluorescence-signal.
 3. The method of claim 2, wherein determining the lubrication oil parameter further comprises determining a steady-state of the light-induced fluorescence-signal from the temporal variation of the fluorescence intensity.
 4. The method of claim 3, wherein determining the lubrication oil parameter further comprises determining the lubrication oil parameter from the steady-state of the light-induced fluorescence-signal.
 5. The method of claim 1, further comprising collecting the lubrication oil sample from an industrial equipment.
 6. The method of claim 1, wherein the light beam is a continuous electromagnetic wave characterized by a single wavelength.
 7. The method of claim 6, wherein the single wavelength is between 200 nanometers and 550 nanometers.
 8. The method of claim 1, further comprising converting the continuous electromagnetic wave into a plurality of step light beams, such that each step light beam has substantially the same intensity within a time interval.
 9. The method of claim 1, further comprising guiding the light beam at an acute angle on a front surface of a container holding the lubrication oil sample.
 10. The method of claim 1, further comprising filtering the light-induced fluorescence signal.
 11. The method of claim 1, further comprising capturing the light-induced fluorescence signal by a fast photodiode.
 12. The method of claim 1, wherein the fluorescence intensity is represented as a second order dynamic system which corresponds to an over-damped oscillator and the damping factor is larger than 1 or smaller than
 1. 13. The method of claim 1, wherein the oil parameter is at least one of associated to an oil viscosity, is a damping factor of the fluorescence signal, is an undamped natural frequency of the fluorescence signal.
 14. The method of claim 1, further comprising: comparing the oil parameter to previously measured oil parameter to determine an oil deterioration rate; and determining an estimate of a useful remaining lifetime of the industrial equipment associated to the lubrication oil sample based on the oil deterioration rate, wherein the industrial equipment is in use in a hydrocarbon-producing well during determining the estimate of the useful remaining lifetime of the industrial equipment.
 15. The method of claim 14, wherein the industrial equipment is a submersible pump configured to pump fluid uphole from the hydrocarbon-producing well and wherein the submersible pump is disposed within the hydrocarbon-producing well.
 16. The method of claim 1, wherein the light beam is generated by a laser source.
 17. A system to diagnose lubrication oil deterioration, the system comprising: a memory; a hardware processor interoperably coupled with the memory and configured to: guide a light beam to a lubrication oil sample; detect light-induced fluorescence signal from the lubrication oil sample; determine a lubrication oil parameter from the light-induced fluorescence signal; and determine an amount of lubrication oil deterioration by correlating the lubrication oil parameter to a calibration curve.
 18. A system, comprising: a light beam generator configured to generate a light beam; a container comprising a lubrication oil sample; an optical equipment configured to guide the light beam to a face of the container; a fast photodiode configured to detect light-induced fluorescence signal from the lubrication oil sample; and a hardware processor interoperably coupled with a memory and configured to: determine a lubrication oil parameter from the light-induced fluorescence signal; and determine an amount of lubrication oil deterioration by correlating the lubrication oil parameter to a calibration curve. 